Avoid hitting the thread check when WebRtcAudioRenderer is going away.

content/renderer/media/webrtc_audio_device_impl.cc

Index: content/renderer/media/webrtc_audio_device_impl.cc
diff --git a/content/renderer/media/webrtc_audio_device_impl.cc b/content/renderer/media/webrtc_audio_device_impl.cc
index ef816fcc60d359c2f150be6fb5ce8cead0108686..7e27af1a08cfac518300914d164e73cac44da714 100644
--- a/content/renderer/media/webrtc_audio_device_impl.cc
+++ b/content/renderer/media/webrtc_audio_device_impl.cc
@@ -175,6 +175,12 @@ void WebRtcAudioDeviceImpl::RemoveAudioRenderer(WebRtcAudioRenderer* renderer) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_EQ(renderer, renderer_);
   base::AutoLock auto_lock(lock_);
+  // Notify the playout sink of the change.
+  for (PlayoutDataSinkList::const_iterator it = playout_sinks_.begin();
+       it != playout_sinks_.end(); ++it) {
+    (*it)->OnPlayoutDataSourceChanged();
+  }
+
   renderer_ = NULL;
   playing_ = false;
 }